Frigging Fuses!

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pos

pos

Well-Known Member
Posts
3,685
Location
West Yorkshire
Hello,

I've just acquired a lucas car horn (12V) that sounds exactly like a ships horn and it's just as loud! I rigged it up earlier using my original horn wiring (just a live feed) and it quickly parped, only to immediately blow the fuse. I then swapped the fuse for another 10 amp fuse which also blew. My 90 is a 1986 with the glass type fuses and there's quite a few things on the circuit. As far as I can see there is the dashboard / cab light, horn and indicators or something all on one fuse. Am I safe to put in a higher amp fuse or is this not the cause of my problem!?

Thanks for any help
-Pos
 
not a good idea to start changing fuse sizes upwards - best to run a seperate feed for the new horn along with a higher rated fuse just for that
 
Thats what I thought. Why does it keep blowing the fuses though!? Its only 12V and it's only got piddly little wires sticking out of it :confused:
 
the current makes the difference between your factory fitted horn and your 'ship horn' the factory fitted one wont draw a lot of current but the one you have fitted will thats why it will be blowing fuses.
the above post is the best way round the problem.
 
Through a relay that's a brilliant idea! So basically, one live feed wire from my battery (could I chip into my spot lights wire?) and then have that wired up to the standard horn cable?
 
Right, I've still got problems, here's the situation.

I've got a thick cable running from my battery directly to a point in my engine bay. From that point, I have my spotlights (via a relay from full beam and my horn via a relay from the original horn feed wire all with their own fuses). When blowing the horn, the original glass 10A fuse is fine, but when I flick to full beam the fuse blows. What's going on here!? Is this because I have two relays on one power line? Also note that the fuses at the relays are 30A, not 10A like the one in the main fuse box.

The main 10A fuse governs:

- Interior Light
- Dashboard Lights
- Horn
- Full Beam Flash (pull towards you on left indicator stalk)

Full beam (including my spotlights) does still work on normal full beam, not flash full beam. What's going on!? Can I just put a higher amp fuse into the fuse box?

Cheers
-pos
 
sounds like your getting a short through the light wires, just run a seperate supply to your horn relay, keeps it simple and seperate from any other systems.
 
But in theory it is a separate system. It's just spliced into a 12V feed wire from the battery terminal as opposed to having its own wire from the exact same spot! :confused:
 
disconnect the horn feed off the lights and try them, if all is well just connect the feed to the horn relay directly to the battery while you try it, if it works you have found your fault. it is easier to have two isolated circuits than trying to piggy back of other circuits and you won't have all this agro if you get faults in the future. makes fault finding a damn sight easier if you know where the system starts and finishes
 
pos said:
Thats what I thought. Why does it keep blowing the fuses though!? Its only 12V and it's only got piddly little wires sticking out of it :confused:
Click to expand...

Nothing to do with the voltage - its just too high a current, or you damaged the wires when you swapped the horn over and its shorting.

Right it sounds to me like you have made a little short somewhere.

You should have coming from a suitable supply a main cable to the relays, this will pass via the relay out to your lights and to your horn. There should be the switching supply into the coil of the relay which will need grounded. So when you peep the horn or flip to full beam you get power down the wire, switches the coil and lets power run from the main input out the otherside to the load in this case your lights or horn.

Did you muddle your pins and your switching the mains to neutral - thus creating a dead short?

Just think of the relay as a switch, find the in and the out, and then treat the little switching wires as a seperate thing. If electrics isn't your strong point put in nice simple circuits, and make them individual.]

Also, ditch the connector block and go for solder and heatshirnk, also makes the joins much smaller and they look neater.
 
Here's a wiring diagram, I'll retrace my steps and try what's been suggested!

wiring.jpg
 
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